Chj-chj



a a free carboxyl group or a 7 containing a free carboxyl 2,875,205 Patented 24, 1 959 United States mam Office DICARBOXYLIC ACID-MONOPIPERAZIDESI AND A PROCESS FOR THEIR MANUFACTURE Heinrich Ruschig and Walter Si edel, Bad Sodeu (Taunus Heinrich Leditschke and Manfred'Schorr, Frankfurt am Main, Dieter Schmidt-Barbe, Hofh eim (Taunus), and Georg Lammler, Frankfurt am Main, Germany, assignors to Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius & Briining, Frankfurt am Main, Germany,.acorporation of Germany No Drawing. Application October 19, 1956 Serial No. 616,924

Claims priority, 'applicationGermany October 29, 1955 7 Claims. (Cl. 260-468) It is known that certain piperazine derivatives, for

active derivative thereof, and, if desired, a compound so obtained and containing no free carboxyl group may be hydrolysed to form the monopiperazide containing compound so obtained and group may be esterified or converted into a metal salt thereof.

The 1- 3 '-halogen-4'-methyl-phenyl -piperazine used as starting material may be obtained,for example, from the corresponding toluidine either by condensation with diethanolamine or areactive ester thereof or by building up the piperazine ring in stages or by introducing the piperazine ring into an appropriately substituted toluene. i i

The halogen atom in ortho-position to the methyl groupin the phenyl nucleus may be any halogen atom, but is preferably chlorine.

As dicarboxylic acids there are suitable those of aliphatic, aromatic or unsaturated heterocyclic character. In the case of aliphatic dicarboxylic acids the carbon chain may be interrupted by a hetero atom, e. g. oxygen or sulphur.

However, a carbon chain need not be present. There may be mentioned, for example, the following dicarboxylic acids; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, tartaric acid, aspartic acid, glutamic acid, diglycolic acid, thiodiglycolic acid, phthalic acid and isomers thereof, or pyridine dicarboxylic. acids.

Instead-ofthe free dicarboxylic acids there can also be used reactive derivativesfthereof, for example, esters, anhydrides, halides, azides ornitriles thereof. As ester components there comeinto consideration alcohols having an alkyl radical with straight or a branched chain containingup to 5 carbon atoms.

The process .of the present invention may be carried out by reacting an appropriately substituted phenylpipera'zine with -a dicarboxylic acid. ester, and subsequently (1950), page 2 hydrolysing the piperazide ester so obtained. It is advantageous to carry out the reaction in the presence of an organic solvent such, fo example,'as an alcohol of low molecular weight,.at room temperature or moderately low or raised temperature. p

In the case of dicarboxylic. acids which form cyclic anhydrides it is advantageous to react the substituted phenyl-piperazine in the absence or in the presence of a solvent with the anhydride of the dicarboxylic acid. As solvents there are suitable, .besides water, also organic solvents, preferably ketones, suchasacetone, or aromatic hydrocarbons such as benzene or toluene. The reaction can be carried out at a. temperature between 10 C. and 200 C., and it is advantageous to work at the boiling temperature of the solvent. used, or in the absence of a solvent preferably between 100 C. and 150 C. i

An alternative method is to treat the appropriately substituted phenyl-piperazine with an ester-chloride of the dicarboxyl ic acid. In this case it is advantageous to work in the presence of an inert solvent. The reaction may be carried out with or without the addition of an acid-binding agent. A's solvents there may be used, for example, halogen-hydrocarbons, aliphatic ketones or ethers or aromatic hydrocarbons. Asfacidbinding agents there may be used inorganic compounds, such as sodium carbonate, calcium carbonate or calcium oxide, or there may be used organic bases, such as pyridine. The piperazide esters obtained in this manner may be hydrolyzed, for example, by means of an alcoholic solution of potassium hydroxide, to form the corresponding dicarboxylic acid monopiperazides.

The process may also be carried out by slowly in troducing the substituted phenyl-piperazine into the dicarboxylic acid dihalide. By subsequently adding Water the desired dicarboxylic acid monopiperazide is obtained directly. i a

Another method consists in heating the appropriately substituted phenylpiperazine with the dicarboxylic acid at a temperature up toabout 200 C. in the absence of a solvent.

The compounds obtained by the process of the invention are generally colourless crystalline products most of which are readily soluble in alkalies and alcohols, but are sparingly soluble in Water EXAMPLE 1 Phthalic acid m 0n0 4(3'-ohl0r0-4'+methylph enyl) -piperazide To a hot solution of 14.8 grams of phthalic anhydride in 100, cc. of benzene there is added a solution of 21.1 grams of l-(3-chloro 4-methyl-phenyl)epiperazine' (colourless oil boiling at 136-137 C. under a pressure of 05 mm. of mercury;.its hydrochloride melts at. 201 C.)

in 50 cc. of benzene.

are obtained. 35 grams of The reaction mixture is heated for one hour on the steam bath. .After cooling there. phthalic acid mono;4- (3f; chloro-4'-methyl-phenyl) piperazide melting at 196 C. I

3 1 A PLE 2 yl-phenyl-) -piperazide To a boiling solution of 15 grams of pyridine-2,3-dic'arboxylic anhydride in 150 cc. of benzene there is added dropwise a solution 'of 21 grams of 1-(3'-ehloro-4-methyl-phenyl)-piperazine in50 cc. of benzene, and the mixture is heated for one hour on the steam bath. By adding, after cooling, ahout200 cc. of petroleum ether the reaction product is precipitated as a viscous oil from which the solvent is decanted off. The reaction product is then taken up in methylene chloride, the solution is washed with dilute acetic acid and water, dried over sodium sulphate, and the methylene chloride is distilled off. The viscous product which remains is covered with petroleum ether, triturated well, and filtered with suction. There is obtained"pyridine-2,3-diearboxylic acid mono-4-(3'-chloro 4'-methyl-phenyl) piperazide in the form of a brownish amorphous powder which agglutinates when heated at temperatures above about 75 C. and which decomposes ahove 100 C. a

7 EXAMPLE 3 Mtzleic acid 7 mono-4-(3-chl0r0-4' methyl-phenyl)-piperazide To 14.8 grams of-maleic anhydride in 140 cc. of benzene there is added dropwise at 30 C. while stirring a solution of 31.6 grams of 1-(3-chloro-4'-methyl-phenyl)- piperazine in 60 cc. of benzene. The reaction mixture is allowed to stand for two days, and the crystalline precipitate is filtered off with suction and recrystallized from ethyl acetate. There are obtained 44 grams of maleic acid mono-4-(3'-chloro-4'-methyl-phenyl)-piperazide, melting at l45-146 C. The methyl ester of maleic acid mono-4(3'-chloro-4'-methyl-phenyl)-piperazide prepared with diazo-methane melts at 56-57 C. after recrystallization from ether.

' EXAMPLE 4 Succinic acid mn0-4-(3-chl0r0-4-methyl-phenyl -piperazide To 15 grams of succinic anhydride in 140 cc. of benzene there is added at 7580 C. a solution of 31.6 grams of l-(3'-chloro-4' methyl-phenyl)-piperazine in 60 cc. of benzene, and the reaction mixture is then maintained for 15-30 minutes at 80 C. After evaporating the benzene the residue crystallizes when triturated with ethyl acetate. After being repeatedly recrystallized from ethyl acetate or acetone, the resulting succinic acid mono-4-(3'-chloro- 4'-methyl-phenyl)-piperazide melts at 115 C., the yield being 23.8 grams.

EXAMPLE 5 Oxalic acid .mono-4-(3'-chl0r0-4-methyl-plzenyl)-piper- L azid'e V I (a) OXAIJIC ACID ETHYL ESTER 4-(3'-CHLORO-4- METHYL-PHENYL) -PIPERAZIDE 25 cc. of drypyridine'and 40 grams of 1-(3-chloro- 4'-methyl-phenyl)-piperazine are dissolved in 100 cc. of dry chloroform, and to the solution there is added slowly, while stirring at 5-10 C., a solution of 26 grams of ethoxalyl'chloride in 25cc. of chloroform. After bemethyl-phenyl)-piperazide melts at 53-55" C. V g

(b) OXALIC ACID MONO-4-(3'-CHLORO-'4'-METHYL- PHENYL) -PIPERAZIDE To a solution of 32.5 grams of oxalic acid ethyl ester 4-(3-chloro-4'-methyl-phenyl)-piperazide in cc. of ethyl alcohol there is added a solution of 9 grams of potassium hydroxide in 20 cc. of water diluted with 30 cc. of ethyl alcohol. After 2 hours the crystalline precipitate formed is filtered off with suction, and recrystallized twice from a mixture of ethyl "alcohol and water in a ratio 9:1. There are obtained 25 grams of the potassium salt of oxalic acid mono-4-(3'-chloro-4 methyl-phenyD-piperazide, which crystallizes. with 1 mol of water and decomposes at 298299 C.

5 EXAMPLE 6 Mul'eic acid mono-'4-(3f-bromo-4'-methyl-phenyl)-pipcr azide 44.7 grams of 1-(3-bromo-4'-methyl-phenyl)-piper aziue in an oil (boiling at 135-136 C/under a pressure of 0.2 mm. of mercury; its hydrochloride melts at 222 C.) are added dropwise, While stirring, at 10-l5 C. to a solution of 19 grams of maleic anhydride in 200 cc. of benzene. After allowing the mixture to stand for 24 hours at 20 C., the crude product is filtered off with suction and recrystallized from ethyl alcohol. There are obtained 42 grams of maleic acid mono -4-(3-bromo-4 methyl-phenyl)-piperazide melting at -156" C.

EXAMPLE 7 piperazid e A mixture of 42 grams of 1-(3'-chloro-4-methyl-phen yl)-piperazine and'50 grams of adipic acid are heated in an open vessel for 4 hours at C. After being cooled the mixture is taken up in 2 N-sodium hydroxide solution, the undissolved matter is filtered off, and the filtrate is decolourized with charcoal and acidified with glacial acetic acid. By taking up in benzene, thoroughly washing the solution with water and drying it and evaporating the solvent, there are obtained 39 grams of a crude product, which, after recrystallization twice from ethyl acetate, yields 28 grams of adipic acid mono-4-(3-chloro 4-methyl-phenyl)-piperazide melting at 103104 C. By methylating this product withdiazomethane and recrystallizing it from a mixt'ure of benzene and ether, there are obtained 21.1 grams of adipic acid methyl ester 4-(3'-chloro-4'-methyl-phenyl)-piperazide melting at 103- 104C. EXAMPLE 8 Adipic acid mono-4-(3'-chl0rq-4'-methyl-phenyl)- W V piprazide To a solution of 64 gramsof crude adipic acid dichloride in 100 cc. of dry benzene there is added dropwise at 5 C. asolution of 67 grams of 1-(3'-'chloro-4'- methyl-phenyl) -piperazine in 250 cc. of benzene. -After' allowing the mixture to stand for a short time water is added, the, solution is. rendered alkaline with sodium hydroxide and the aqueous phase is separated from the benzene phase and the undissolved material. By acidifying the aqueous phase with glacial acetic acid and ex-- traction with benzene, there are obtained 19.5 gramsof. crude adipic acid mono-4-(3'-chloro-4-methyl-phenyl)-. piperazide, which, when recrystallized from ethyl acetate,

melts at 103 C. 1

EXAMPLE 9 M alonjc acid methyl ester 4-(3-chZoro-4-methyl-pltenyl)- piperazide 90 grams of 1-(3-chloro-4'-methyl-phenyl)-piperazine arefadded .16 grams of NaOH dissolved in 30cc. .of"vfater anddiluted-with 50 cc. of ethyl alcohol. [.The fsodium salt. of malonic acid mono-4-(3'achloro-4 methyl-phenyl); piperazide, which crystallises rapidly, is filteredl'olfwith suction, allowing the mixture to stand for a short time, Washed with ethyl alcohol, and decomposed by dissolving it in water and adding acetic acid. There are obtained about 44 grams of malonic acid mono-4-(3'-chloro-4- methyl-phenyl)-piperazide which, after recrystallization y;

from methanol, melts at 133 C. (with decomposition). The methyl ester of the latter acid cannot be crystallized or distilled. It can be obtainedin a pure form as a nearly colourless viscous oil by methylation with diazomethane.

EXAMPLE 1() Glutaric acid mono-4-(3'-chl0ro-4'-melhyl-phenyl)- piperazide reflux for 1-2 hours, cooled, washed with 0.5 N-hydromula:

chloric acid and water, and the solvent is evaporated. The residue crystallizes after the addition of a few crystals of a previously prepared sample of. this product. By repeated recrystallization from ethyl acetate, 83 grams of glutaric acid mono-41 (3 '-c hloro-4'-methyl-phenyl) -piper azide melting at 98-99 C. are obtained. The methyl ester obtained by methylation with diazomethane melts at 67-68 C. after recrystallization'from ether.

' EXAMPLE ll Terephthalic acid mn0-4-(3'-clzl0ro-4'-mezhyLphenyl)- piperazide 56 grams of terephthalic acid dichloride are dissolved in 350 cc. of benzene, a solution of 58 grams of l-(3- chloro-4'-rnethyl-phenyl)-piperazine in 50 cc. of benzene is added dropwise, and the mixture is stirred for 1 hour. To thick magma so formed there are added about 100 cc. of Water, and the reaction mixture is boiled for a short time, while stirring, and the undissolved tereph-. thalic acid bis- -(3'-chloro-4'-rnethyl-phenyl)-piperazide is filtered off with suction. To the filtrate sodium hydroxide solution is added until the reaction becomes alkaline, the mixture is agitated, the aqueous layer is separated, and the terephthalic acid n1ono-4-(3-chloro- 4-methyl-phenyl)-piperazide is precipitated by adding dilute acetic acid. By recrystallizing the product from a mixture of alcohol and water, it is obtained as a yellowish powder melting at 155-l57 C. (with decomposition).

EXAMPLE l2 Succinic acid mono-4-(3'-chl0r0-4-methyl-phenyl)- piperazide obtained 23 grams of succinic acid mono-4-(3'-chloro-4'- methyl-phenyl)-piperazide in the form of colourless crysa tals melting at 115-1 19 C.

EXAMPLE 13 Diglycollic acid mono-4-(3-chloro-4-mefhyl-ph enyl)- piperazide To a solution of 23.2 grams of diglycollic anhydride in 150 cc. of boiling benzene is added dropwise a solution of 42 grams of 1-(3'-ch1oro-4-methyl-phenyl)-piperazine in 50 cc. of benzene, the mixture is heated under reflux for 30 minutes, cooled, and the crystals which separate EXAMPLE 14 Thfodiglycollic acid mono-4-(5"-chloro-4-methyl-phenyl)- piperazide To a solution of 26.4 grams of thiodiglycollic anhydride in cc. of boiling 'benzlene is added dropwise a solution of 42 grams of 1-(3-chloro-4'-methyl-phenyl)- piperazine in 50 cc. oftbenzene, and the mixture is heated at the boil for one hour. After cooling the mixture there is slowly added thereto about twice its volume of petroleum ether, whereby, a rviscousmoil'is precipitated which solidifies after prolongedstanding. The precipitate is filtered off with suction and recrystallized from a little ethyl acetate. There is obtained, thiodiglycollic acid mo'no4-(3-chloro-4'-methyl-phenyl)-piperazide in the form of colourless crystals melting at 102104 C.

We claim:

1. A member selected from the group consisting of dicarboxylic acid-monopiperazides of the general fordimethylene ether, dimethyle'ne thioether, lower alkenylene, phenylene and pyridine groups, n represents a number selected from the group consisting of 0 and 1, and lower alkyl esters and non-toxic metal salts of the acids of the above formula.

2. The compound of the formula:

r A o1- I oo coon s :7 4. The compound of theiformula:

w LT CH1 CH2 (:30 300E CHz-O-OH: 6. The compound of the formula:

I CO C0011 7. In the process for preparing a member selected from the group consisting of dicarboxylic acid-monopiperazides and lower alkyl esters and non-toxic metal Salts thereof, said dicarboxylic acid-monopiperazides having the general formula:

Z I CH3 Hal- ' wherein Hal represents amember selected from the group consisting of chlorine and bromine, X represents a member selected from the group consisting of lower alkylene, dimethylene ether, dimethylene thioether, lower alkenyle ene, phenylene and pyridine groups, n represents a number selected from the group consisting of 0 and 1, the step which comprises heating l-(3-halogen-4'-methylphenyl)-piperazines with a member selected from the group consisting of dicarboxylic acid and the lower alkyl esters, inner anhydrides and chlorides thereof at a temperature within the range of about 5 to 200 C.

No references cited. 

1. A MEMBER SELECTED FROM THE GROUP CONSISTING OF DICARBOXYLIC ACID-MONOPIPERAZIDES OF THE GENERAL FORMULA: 